The present invention relates to a noise cancellation method, a receiver circuit that receives a communication signal modulated by a direct sequence spread spectrum method, and an electronic instrument including the receiver circuit.
A phenomenon referred to as crosstalk in which a signal transmitted through one channel is superimposed on another channel has been known. Since crosstalk causes a significant deterioration in signal quality, various technologies have been proposed to prevent crosstalk or remove a mixed crosstalk component. For example, technology that removes a crosstalk component by generating a signal (cancellation signal) that cancels (attenuates or removes) a mixed crosstalk component (see U.S. Pat. No. 7,050,388) has been developed.
In an electronic instrument including a receiver circuit, an alternating current signal may be generated due to a change in electromagnetic field caused by the circuit operation of an electronic circuit disposed near the receiver circuit. The alternating current signal may be transmitted to the receiver circuit and mixed into the received signal as an interference wave. Noise cancellation technology that cancels the interference wave superimposed on the received signal by generating a cancellation signal and adding the cancellation signal to the received signal has been known.
However, noise may not appropriately cancelled using this noise cancellation technology. Specifically, an interference wave may not be accurately detected (e.g., only part of the interference signal is detected, or the interference signal is detected in a state in which part of the signal which should be received is mixed). In this case, the mixed interference wave may be removed to only a small extent, or the signal which should be received may be partially attenuated.